/* Auteur: Nicolas JANEY                */
/* Avril 2001                           */
/* Gestion des transparences en OpenGL  */

#include "windows.h"

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>

#include <stdio.h>
#include <math.h>

static GLfloat view_rotx=1.0F ;
static GLfloat view_roty=1.0F ;
static GLfloat view_rotz=1.0F ;

void myinit(void) {
  GLfloat light_ambient[] = { 0.0F,0.0F,0.0F,1.0F };
  GLfloat light_diffuse[] = { 1.0F,1.0F,1.0F,0.5F };
  GLfloat light_specular[] = { 0.0F,0.0F,0.0F,1.0F };
  GLfloat light_position0[] = { 1.0F,1.0F,1.0F,0.0F };
  glLightfv(GL_LIGHT0,GL_AMBIENT,light_ambient);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,light_diffuse);
  glLightfv(GL_LIGHT0,GL_SPECULAR,light_specular);
  glLightfv(GL_LIGHT0,GL_POSITION,light_position0);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_AUTO_NORMAL);
  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LESS);
  glEnable(GL_ALPHA_TEST);
  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
  glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
}

void display1(void) {
  float rouge[] = { 1.0F,0.0F,0.0F,0.5F };
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  glRotatef(view_rotx,1.0,0.0,0.0);
  glRotatef(view_roty,0.0,1.0,0.0);
  glRotatef(view_rotz,0.0,0.0,1.0);
  glPushMatrix();
  glMaterialfv(GL_FRONT_AND_BACK,GL_DIFFUSE,rouge) ;
  auxSolidBox(17.0,5.0,10.0) ;
  glPopMatrix();
  glPopMatrix();
}

void display2(void) {
  float blanc[] = { 1.0F,1.0F,1.0F,0.5F };
  glPushMatrix();
  glRotatef(view_rotx,1.0,0.0,0.0);
  glRotatef(view_roty,0.0,1.0,0.0);
  glRotatef(view_rotz,0.0,0.0,1.0);
  glMaterialfv(GL_FRONT_AND_BACK,GL_DIFFUSE,blanc) ;
  glPushMatrix();
  auxSolidBox(9.0,9.0,18.0) ;
  glPopMatrix();
  glPopMatrix();
}

void CALLBACK display(void) {
  glEnable(GL_DEPTH_TEST);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glPushMatrix() ;
  display1() ;
  display2() ;
  glPopMatrix() ;
  glFlush();
  auxSwapBuffers() ;
}
void CALLBACK myReshape(int w,int h) {
  glViewport(0,0,w,h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-11,11,-h*11.0/w,h*11.0/w,-15.0,15.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

void CALLBACK keyx(void) {
  view_rotx += 2 ;
}

void CALLBACK keyX(void) {
  view_rotx -= 2 ;
}

void CALLBACK keyy(void) {
  view_roty += 2 ;
}

void CALLBACK keyY(void) {
  view_roty -= 2 ;
}

void CALLBACK keyz(void) {
  view_rotz += 2 ;
}

void CALLBACK keyZ(void) {
  view_rotz -= 2 ;
}

void main(void) {
  auxInitDisplayMode(AUX_DOUBLE|AUX_RGB|AUX_DEPTH);
  auxInitPosition(0,0,300,300);
  auxInitWindow("Transparences");
  myinit();
  auxKeyFunc(AUX_x,keyx) ;
  auxKeyFunc(AUX_X,keyX) ;
  auxKeyFunc(AUX_y,keyy) ;
  auxKeyFunc(AUX_Y,keyY) ;
  auxKeyFunc(AUX_z,keyz) ;
  auxKeyFunc(AUX_Z,keyZ) ;
  auxReshapeFunc(myReshape);
  auxMainLoop(display);
}